Catalytic conversion of hydrocarbons



Patented Aug. 27, 1946 OATALYTIO CONVERSION oF HYDROCARBONS Nelson B. Haskell, Port Arthur, Tex., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application June 25, 1943, Serial No. 492,210

6 Claims. 1

This invention relates to a continuous process for effecting catalytic conversions of hydrocarbons such as isomerization of saturated hydrocarbons. v

The invention has to do with the catalytic conversion of hydrocarbons by the action of a conversion catalyst comprising metallic halide-hydrocarbon complex. It involves effecting the reaction during passage of the hydrocarbons undergoing treatment through a plurality of sepasisting essentially of aluminum chloride-hydrocarbon complex liquid characterized by having rate reaction zones, each zone containing como plex catalyst liquid containing a different concentration of metallic halide..

In accordance with the invention a stream of feed hydrocarbons is subjected to contact under conversion conditions with a liquid catalyst which comprises metallic halide-hydrocarbon complex having a relatively high content of metallic halide. Thereafter the hydrocarbon products containing some metallic halide in solution are subjected to contact with complex liquid having a relatively low content of metallic halide and capable of removing the dissolved metallic halide from the hydrocarbon products so that the hydrocarbon products are discharged from the nal reaction zone of the process substantially free from metallic halide. The complex liquid used for making this final contact with hydrocarbon products of reaction becomes enriched in metallic halide and is used in a separate zone for treating a separate stream of fresh feed hydrocarbons under conditions such that at least partial conversion is effected. The hydrocarbon products of reaction from this separate reaction zone are passed to the first-mentioned reaction zone containing catalyst of relatively high metallic halide content.

In this separate reaction zone the metallic halide content of the complex liquid is reduced thereby forming a relatively lean complex which may be used for effecting removal of dissolved metallic halide from the hydrocarbon products in the nal reaction zone.

Also in accordance with the invention a separate stream of feed hydrocarbons may be passed directly to the main reaction `zone containing the complex catalyst of relatively high metallic halide content and make-up metallic halide may be dissolved in this separate stream of feed hydrocarbons so as to compensate at least in part for metallic halide disappearance from the system and particularly from the main reaction zone wherein it is desired to maintain a relatively high concentration of metallic halide.

The invention has particular application in the isomerization of saturated hydrocarbons with an aluminum halide catalyst such as aluminum chloride. Thus in carrying out the process as applied to the isomerization of hydrocarbons with an aluminum chloride catalyst it is contemplated emf ploying in the main reaction zone a catalyst cona heat of hydrolysis of about 350 calories or more per gram of complex liquid or having a heat of hydrolysis substantially above about 320 to 330 calories per gram of complex liquid. Such complex liquid will contain free aluminum chloride which may be present as a solution in the complex liquid or may be suspended therein as undissolved solid aluminum chloride. It may be present in both dissolved and suspended form. The catalystV may consist of molecularly dispersed aluminum chloride in a complex formed by the reaction of aluminum chloride with an aliphatic hydrocarbon;

The stream of hydrocarbon products issuing from this main reaction zone will' contain a substantial amount of dissolved aluminum chloride. This stream is then passed through another re.- action zone 'wherein itis subjected to contact with complex liquid which is relatively lean in free aluminum chloride, -being characterized, for example, by having a heat of hydrolysis of not more'than about 260 calories per gram of complex liquid or substantially below about 320 to 330. As a result of this contact the lean complexV becomes enriched with aluminum chloride which it has removed from the hydrocarbons undergoing treatment andthe treated hydrocarbons may be discharged free or substantially free from aluminum chloride.

Contact between the hydrocarbon products and complex liquid of relatively low aluminum chloride content is continued until the complex liquid has become enriched and is characterized by having a heat of hydrolysis in the range about 300 to 320 calories per gram. Thereafter the enriched complex is removed from further contact with hydrocarbon products of reaction and is used for treating another and separate stream of feed hydrocarbons. This separate stream is subjected to contact with the enriched complex under isomerizing conditions so that at least partial isomerization of the hydrocarbons is effected and is accompanied by a progressive decrease in the aluminum chloride concentration of the complex. When the aluminum chloride content has been Vdecreased so that the complex liquid is characterized by having a heat of hydrolysis of not more than about 260 calories per gram of complex it is removed from further contact with fresh feed hydrocarbons and is then used all or in part for contact with hydrocarbon products in the final reaction zone.

In each of the foregoing operations contact between hydrocarbonsand complex of different aluminum chloride concentration is advantageously effected in the presence of a promoter such as hydrogen chloride and under tempera- .ture conditions such Ythat isomerization constitutes the principal reaction.

An important.- advantage of the process has-.to do Withtheemployment in at leastbne stageiof the process of a complex liquid catalyst which contains free metallic halide amount and beyond that required for forming the complex compounds.

It has been found that a complex liquidcatalyst' containing free metallic halide Aiseiltective inproducing a high rate of conversion. Atythefsame time, however, there is an appreciable amount of metallic halide migration from the reaction Zone, the metallic halide being dissolved in the'eiuent hydrocarbon stream and thus being carriedout of the reaction zone. The disappearance of metallic .halide from the reaction zone is undesirablefrom the. standpoint. of ,maintaining a.. uniformly `high level of conversion. The. presence ofthe dissolved aluminum. halide. inv .the eluent. hydrocarbon stream resultsfin accumulation orprecipitation. of

lthe metallicfhalide. in subsequent.. stages ofT the .process unless provisionis ,made for effecting-its removal.

Therefore, in accordance with the;present .in vention `the .eiuent hydrocarbon streamissubjected to intimatecontactwithcomplex/liquid which is. relatively. lean. Vin lfree .metallic.' halide. It' hasybeen .found that `this lean. complex .liquid yexerts preferential solvent. action' forthe. .metallic halide and thereby effects its removalfrom-the hydrocarbon products .in `whichthe metallic Whalide may .bepresentas a. solute. ,lnthis-way. the lean complexliquid is. .enriched .and the Yresulting enriched complex may.. .then be v.utilized in effecting catalytic; conversion ..of, at'. least abortion Aof .thefresh.feedhydrocarbons It has. been found thatan.aluminumbhloridehydrocarbon complex liquid characterized by. having a heat of hydrolysis inthe range about 200 to 260, calories poly-gram of .complex liquid iscapable of effecting removal of aluminum halide'. from-.so-

lution in hydrocarbons and will. continue to. exert this. effect until it is. characterizedbyhaving. a

heat of. hydrolysis inthe range .about 3 00..to 320 calories per. gram. As.. soon as vthe .heat off hydrolysis reaches a substantially higher valuealumnllm halide is given. up.. and is ,extractedthere- 'from bythe .hydrocarbons with .which the. com- .plex isbrought intoohtact In order todescribelthe processor 'the .inyenton in .more detail referencewillnow be. made tothe accompanying .drawing comprising a.. diagram of l dov/'illustrating ,one method of practicing-themvention as applied tothe isomerization of normal butane with an aluminumchloride catalyst. prol moted'wth hydrogen chloride.

Referring to the drawing normal butane is conductedgfrom asource notshown througha pipe I and passed through a heater 2 wherein it is heated to a temperatureof about`200 F. or to a tempera- `turewithin the range 160 to 240". F. A portion .of theheated stream is diverted through a branch pipe3' and. introduced to thelower portion of a main reactionl tower. 4. In the reactor` 4. itsub-r jected to contact'with aluminumlchloride-hydrocarbon-complex liquid `catalyst characterized by *having-a heat ofhydrolysis'inv the range about i330 to j350 calories-pergram of catalyst" liquid. f Contact between the heated hydrocarbons andthe catalyst liquid is effected in the presencehighy- `drogen chloride under conditions VV:such that isomerization` constitutes the principal" reaction. I 'The converted and unconverted Ahydrocarbons are continuously discharged from the upper portion v of the `reactor 4 through a4 pipe-'Sand' the'discharged hydrocarbons will )contain a vsmall in substantial" --iamount of. dissolved v.aluminum chloride, for ex- ;am'ple about 0.01 to 01.20% by Weight. The discharged hydrocarbons are conducted through a -branch pipe 6 to the lower portion of a nal reactor '1. In this iinal reactor the hydrocarbons '-areisubjected to contact with aluminum chloridehydrocarbon complex liquid having a heat of hy- ...d-rolysis not in excess of about 300 to 320 calories Per-gram ofxcomplex and preferably having a heat .fof xhydrolysissubstantially below this, as, for example, about. 260 calories, or in the range or about "200 `to 300 calories per gram. The contact is also effected-in the presence of promoter at a temperature corresponding approximately to that prevail- .ingin the reactor 4.

'Theisomerization reactionV being slightly exo- .'thermic. the .hydrocarbon stream leaving .the reactor 4 will be at an elevated temperature` which maybe suiiicientto. maintain .thedesired temperature inthe reactor l. .,However, it is contemplated that .a differenttemperature may be main- Y tained in. thereactor 'I .eithcr below or above-that carbons may be'fractionated from .unreacted hy- ;drocarbonstopermit segregation-.of the unreacted hydrocarbons for recycling throughrthe'system Vif desired.

preyalinggin vthe-reactor LA stream .of .hydrocarbons .comprising isomerized hydrocarbonsand .substantially vfree from aluminum.. halide .is...c ontinuously drawn oi from the upper portion. f.V the. reactor {.through a pipe 8 communicatingwitha discharge pipe which advantageously communicates with suitable fractionating `equipment .wherein isomerized hydro- Theovv of converte-:i hydrocarbon lproducts through the reactor 1 is continued until the. com- :plex rcatalyst liquid thereinhasbecome enriched With.'aluminum. chloride to theextent. that it is characterized by havingaheat of 4hydrolysis of ab'out'300 toi 320,.calories per gram. of4 complex. Thereafter thehydrocarbon product stream yfrom .the reactor vLisdiverted .from .the reactor l and 4.insteadpassedthrough abranclrpipe. l leading j to a reactor i6. In other .words the direction of iflow is reversed before .the .complex inthe reactor 1' becomes saturated with aluminum chloride so .that-itfails to remove-it entirely from the hydrocarbons passingj therethrough.

'In thereactor. i0. the..,hydrocarhofi stream is .broughtinto contactwith complex liquid of .low

`'aluminum chloride content such as initially' used .in. the reactor.` 1. ...The eiiluent stream ofnhydrocarbonsl. from thereactor. lli free fromaluminum halideisfdl'awn oi througha pipe i which'com- .rnunicates with.. the previously mentioned pipe- 9.

'When the, product.stream has been diverted from the reactor 1 a separatestream. of heated butane. feed, .is conducted. from the heater 2 through apipef lilleading to thelower portion 'of the. reactor. l. Sincethecomplex retained in the reactor 'l has been enriched withalurninum chloride it is relatively active as ,an isomerization catalystso .that butane feed. passing therethrough in the .presence of. promotenundergoes .isomeri- `zation to asubstantial extent. .'During .this operaof the complex therein has become diminished so that the heat 'of hydrolysis of the'complex is reduced to about 260 calories per gram or lower. Thereupon the ow of hydrocarbons through the reactors 1 and I6 is reversed. f Y K Y ADuring the time that the reactor Tis being used as a final stage reaction zone theV separatev stream of feed butane flowing through the pipe I8 is conducted through a branch pipe 22 leading to the lower portion ofthe .reactork I6. During passage of the heated feed Vbutane through the reactor I6 the enriched complex now present therein undergoes a decrease in its aluminum chloride content. The outlet stream of hydrocarbons from the vessel IS during this period is drawn off through a pipe 23 which communicates with the pipe 2l previously mentioned.

Another separate stream of normal butane feed is passed through a pipe 30 to a heater or heat exchanger 3l and from there passed to a solution vessel 32. The solution vessel 32 is filled with granular or lump aluminum chloride which may be introduced to the vessel from a hopper 33.

During passage of the butane stream through the vessel 32 solution of aluminum chloride in the butane occurs. The resulting solution is conducted through a pipe 34 to the lower portion of the reactor 4. I

The proportion of butane feed diverted through the vessel 32 andthe temperature to which it is heated prior to passage therethroughwill depend upon the amount of aluminum chloride which it' is desired to introduce to the reactor 4. As previously intimated it is contemplated maintaining the liquid catalyst within the reactor 4 at arelatively high level of activity. Since there is some disappearance or migration of aluminum halide from the reactor 4, it is necessary, therefore, to add make-up 'aluminum halide to compensate for this catalyst disappearance. y

Advantageously sufficient aluminum halide is added so that the. body of liquid catalyst Within the reactor 4 will have a heat ofl hydrolysis ranging from 330 to' 350 caloriesper gram of catalyst liquid. f j f The amount of normal butanediverted-thrugh the-vessel 32 may amount toabout 10 to -15% by volume of the total butane vcharged to the process and the solution temperature prevailing inthe vessel 32 may range from room temperature to 150 F. or to a temperature approximating that prevailing within the reaction vessel 4.

rIhe proportion of normal butane`feed passed directly throughV the pipe 3 to the reactionfvessel 4 may range from about 0 to 50%*by'volume of the total butane chargedto the process'.

The hydrogen chloride promoter is drawn fromv l a source not shownthrough a pipe 40 and in part conducted directly to the reactor 4 while the remainder is conducted through a branch pipe 4l communicating with the previously mentioned pipe i8 by which means the promoter is introduced to either or both vessels 1 or I6; While promoter may beused simultaneously in the three vessels 4. 'l and l5, it is'preferred to inject it to either of the Vessels 'l and l'only" during the period Ythat such vessels are lemployed for effecting contact between fresh feed butane and enriched complex. I 'Y It is advantageous whenv employing anv alumi num halide-hydrocarbon complex type of catalyst to provide for separate injection of promoter and make-up aluminum halide to the reaction vessel 6 4,'-that is; whenfadding the hydrogen'chloride and aluminum halide in solution in feed hydrocarbons it is contemplated employing separate streams of feed hydrocarbon for this purpose and separately injecting them into vthe reaction ves- In the preferred mode of operation the reactionvessels comprise unpacked vertical towers containing a stationary column of complex liquid catalyst,y the height of the liquid column ranging from about 10 to 60 feet and Ypreferably being about 25 to 40 feet in height. The feed hydrocarbons are introduced to the lower portion of the liquid columnv in dispersed liquid phase and caused to rise in dispersed phase through the stationary column of complex by difference in gravity and without subjecting the catalyst liquid to mechanical stirring.

While the use of non-stirred and non-packed towers is mentioned, nevertheless the method of operation is applicable withA packed reaction towers, or with mechanically agitated reactors.

Complex liquid catalyst may be initially prepared by reacting aluminum chloride with an aliphatic hydrocarbon in the presence of hydrogen chloride at temperatures in the range to 300 F. for example. An effective preformed complex may beprepared by reacting aluminum.

While aluminum chloride has been mentionedy in preparing the complex catalyst it is contemplated that other metallic halides including aluminum bromide may be employed. Likewise the promoter used in preparing the complexl or in effecting the conversion reaction may comprise other hydrogen halides besides hydrogen chloride. TheY conversion reaction may be `carried out in the presence of other agents such ashydrogen and normally gaseous saturated hydrocarbons. It may also ber carried out in the presence of inhibiting agents which are useful in suppressing undesired side reactions such as cracking and catalyst deterioration. Such inhibitors include naphthene hydrocarbons such as cyclohexane.

In some cases a low boiling aromatic hydrocarbon such asbenzene in smallamount may be useful in suppressing or inhibiting cracking and catalyst deterioration. v

Isomerization of hydrocarbons other than normal butane may be carried out by means of the process described. For example, other hydrocarbons which maybe isomerized comprise pentane, hexane, heptane, mixtures thereof and also fractions of naphtha which are substantially free froml oleilnic` andV benzenoid or aromatic hydrocarbons. i

f It. is contemplated also that the procedure de-v scribe'd'may have application in effecting other conversion( reactions besides isomeriz'ation, wherein a metallic halide-hydrocarbon complex type of catalyst is used at temperatures ranging from normal room temperature to about 300? 1i.Y

Mention has been made of isomerizing normal butane in the liquid phase. However, it is contemplated 4that 'thev rconversion reaction may be eiected 'with hydrocarbons undergoing treatment in either the gas or liquid phase, or in mixed phase.

`The amountof promoter employed may range from 0.1 to 5% or more by weight of the feed hydrocarbons charged to the process.

In connection with the method of flow specifically illustrated in the drawing it is contemplated `that instead of reversing the hydrocarbon flow through the reaction vessels 'l and Iii, the vessels may be arranged for continuous ow in one direction therethrough with provision for transferring the complex liquid from one to the other. In this way the nal contact between hydrocarbon. products and lean complex liquid is continuously made in the same reaction zone.

Obviously many modiiications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and,v therefore, only such limitations. should be imposedas are indicated in the appended claims.

I claim: v

1. In a continuous process for isomerizing normal butane the steps comprising passing a stream of normal butane in liquid phase through a primary reaction zone, subjecting said butane in liquid phase to contact therein with a liquid catalyst consisting essentially of aluminum chloride-hydrocarbon complex and aluminum chloride, said catalyst having la heat of hydrolysis of about 330 to 350 calories per gram of catalyst, effecting said contact in the presence. of hydrogenhalideat a predetermined temperature in the range of about 160 to 240 F. such that isomerization constitutes the principal reaction, passing a stream containing isomerized hydrocarbons and dissolved aluminum chloride from said primary zone through a secondary zone, subjecting the hydrocarbons in the secondary zone to contact in liquid phase with liquid aluminum chloride-hydrocarbon complex having a heatv of hydrolysis of about 260 to 300 calories per gram of catalyst, effecting said secondary contact in the presence `of hydrogen halide at a temperature in the aforesaid range such that extraction of aluminum chloride from the entering hydrocarbon stream occurs, removing from said secondary reaction Zone a stream of treated hydrocarbons substantially free from dissolved aluminum chloride, and producing as a result of said secondary contact a complex cata- D lyst liquid enriched with aluminum chloride, separately subjecting another stream of normal butane to contact with said enriched complex under conditions such that isomerization constitutes the principal reaction and such that said enriched complex becomes denuded of aluminum chloride, and passing said separately -treated hydrocarbons to said primary zone.

2. The process according to claim 1 in which a small amount of make-up aluminum chloride is continuously introduced to said primary reaction zone.

3. A continuous isomerization process comprising passing a parain hydrocarbon feed comprisingl normal butane in liquid phase through a primary reaction zone, subjecting said feed in liquid phase .to contact therein with a liquid isomerizationcatalyst consisting essentially of aluminum halide-hydrocarbon complex and aluminumhalide, said catalyst having a heat of hydrolysis in excess of about 320 calories per gram of catalyst, effecting said contact in the presence of hydrogen halide at a predetermined temperature in the range of about .to 300 F. such that isomerization constitutes the principal reaction, passing a stream containing isomerized hydrocarbons and dissolved aluminum halide from said primary Zonegthrough a, secondary zone, subjecting the hydrocarbons in the secondary zone to contact in liquid phase with liquid aluminum halide-hydrocarbon complex having a heat of hydrolysis of about 260 to 300 calories per gram of catalyst, effecting said secondary contact in the presence of hydrogen halide at -a temperature in the aforesaid range such that extraction of aluminum halide from the entering hydrocarbon stream occurs, removing from said secondary reaction Zone a stream of treated hydrocarbons substantially free from dissolved aluminum halide and producing as a result of said secondary Contact a complex catalyst liquid enriched with aluminum halide, separately subjecting another stream of said feed hydrocarbons to contact with said enriched complex under conditions such that isomerization constitutes the principal reaction and such that said enriched complex becomes denuded of aluminum halide, and passing said separately treated hydrocarbons to said primary Zone.

4, The process according to claim 3 in which a small amount of make-up aluminum halide is continuously introduced -to said primary reaction Zone.

5. A continuous isomerization process comprising passing a paraffin hydrocarbon feed comprising normal butane in liquid phase through a primary reaction zone, subjecting said feed in liquid phase to contact therein with a liquid isomerizaton catalyst consisting essentially of aluminum chloride-hydrocarbon complex and aluminum chloride, said catalyst having a heat of hydrolysis of .about 330 to 350 calories per gram of catalyst, eifecting said contact in the presence of hydrogen halide at a predetermined temperature in the range of about 100 to 300 F. such that isomerization constitutes the principal reaction, passing a stream containing isomerized .hydrocarbons and dissolved aluminum chloride from said primary zone through a secondary Zone, subjecting the hydrocarbons inthe secondary zone to contact in liquid phase with liquid aluminum chloride-hydrocarbon complex having a heat of hydrolysis of about 260 to 300 calories per gram of catalyst, effecting Said secondary contact in the presence of hydrogen halide at a temperature in the aforesaid range such that extraction of aluminum chloride from the entering hydrocarbon stream occurs, removing from said secondary reaction zone a stream of treated hydrocarbons substantially free from dissolved laluminum chloride, and producing as a result of said secondary contact a complex catalyst liquid enriched with aluminum chloride, separately subjecting another stream of said feed hydrocarbons to contact with said enriched complex under conditions such ythat isomerization constitu-tes the principal reaction and such that said enriched complex .becomes denuded of aluminum chloride, and passing said separately treated hydrocarbons to said primary zone.

6. The process according to claim 5 in which a small amount of make-up aluminum chloride is continuously introduced to said primary reaction zone.

Y NELSON B. HASKELL. 

